A novel fluid-filler/polymer composite as high-temperature thermally conductive and electrically insulating material

Liquid paraffin microcapsules (LPMs) were incorporated into epoxy resin to prepare fluid-filler/polymer composite materials in this work, with the objective of introducing fluid heat convection into thermally conductive and electrically insulting materials. The LPMs were fabricated by coating urea resin onto liquid paraffin via in-situ polymerization, enabling the as-prepared LPMs to experience no weight loss below 240 °C. The heat dissipation efficiency of the LPM/epoxy-resin composite with 25 vol% LPM content was remarkably improved above 50 °C, although its thermal conductivity was only 0.25 W/(m·K) at room temperature. The enhancement of heat dissipation efficiency above 50 °C could be ascribed to the effect of fluid heat convection in the LPM filler increased with increasing temperature. The LPM/epoxy composites containing 20 vol% of LPM filler exhibited tensile strengths, bending strengths, and breaking elongations that were 14.3%, 12.5%, and 30.5% higher, respectively, than those of the pure epoxy resin. The results of this study indicate that fluid heat convention is of great significance in the development of thermally conductive and electrically insulting materials.